The field of the invention is in the electronic collision avoidance art.
At the present day, both the Federal Aviation Agency (FAA) and Department of Defense (DOD) use the air traffic control radar beacon system (ATCRBS) as the primary means of controlling U.S. air traffic. The ATCRBS network consists of nearly 700 ground stations, 184,000 aircraft transponders, and 108,000 altitude encoders for Mode C altitude reporting. It is estimated that DOD owns 108,000 transponders. The U.S. ATCRBS hardware is compatible with the Secondary Surveillance Radar (SSR) international air traffic control system governed by the International Civil Aviation Organization (ICAO).
At least one U.S. pilot experiences a near miss incident every day. A solution to provide a collision-avoidance capability for all aircraft--commercial, business, private, foreign, and military-13 has been needed and, for economic reasons, should make use, if possible, of the existing on-board ATCRBS equipment.
The FAA has studied two developmental beacon collision-avoidance systems (BCAS)- (1) Litchford trimodal (active, passive, active and passive) BCAS, and (2) Miter/FAA active BCAS (A-BCAS). Each system is relatively expensive, due to using sophisticated and complex hardware. For additional background on these systems see: "Avoiding Mid-Air Collisions" by Litchford, George G., IEEE Spectrum, 41, September 1975 and "Collision Avoidance System Evaluated" by Klass, Philip J., Aviation Week and Space Technology, 55, Mar. 1, 1976. The following patents set forth the best known art available in regard to the present invention. U.S. Pat. No. 4,021,802 to patentee George B. Litchford; U.S. Pat. No. 3,882,497 to patentees Klass et al; U.S. Pat. No. 3,792,472 to patentees Payne et al; and U.S. Pat. No. 3,208,064 to patentee John S. Morrel.
Generally the prior art systems, if carried by all large aircraft, will protect large aircraft from each other and small aircraft, but the very high costs of these systems prohibit their general acceptance by all aircraft owners. The presently disclosed system at a cost per installation of less than approximately onetenth the prior art systems provides a practical system for all aircraft owners.